Replace 'Starter POM' by 'Starter' in the documentation

[snicoll]

I find the "POM" part a bit confusing. Our starters are jar artifacts and all that's required is to add a groupId and artifactId.

POM may lead the user to think this is a BOM or that they should add the <type>pom</type> to the declaration to make it work.

Thoughts?

[snicoll]

I've also updated the release notes for 1.4